Fuel pump



Nov. 6, 1934. E. A. RocKwl-:LL 1,980,091

FUEL PUMP Filed sept. 1o, 195o 2 slams-sheet 1 hnl: EME u NOV. 6, 1934.E, A. ROCKWELL FUEL PUMP 2 Sheets-Sheet 2 Filed Sepb. lO. 1930 EdwardQjacwell,

Patented Nov. 6, 1934 FUEL PUMP Edward A. Rockwell, Chicago, Ill..Application september 1o, 1930, serial No; 480,865

6 Claims.

This invention relates to improvements in fuel pump construction of thetype that is adapted to be actuated by the engine for the delivery offuel from the supply tank to the carbureter of the engine in which thefuel is delivered from the pump in accordance with the flow permitted bythe float chamber of the carbureter.

A commercially successful fuel pump has been previously designed whichconsists of a pair of casing parts clamping therebetween a pumpingdiaphragm which is urged in a discharge direction by a compressionspring held between the lower casing part and the bottom of thediaphragm, the diaphragm being actuated in a suction direction vthrougha stem guided for movement by the lower casing part and engaged by alever carried by a fulcrum pin in the'lower casing part and including anarm protruding from the pump so that the pump, as a unit, may be mountedon the engine casing adjacent an aperture thereof, whereby theprotruding arm of the lever comes into thrust engagement with a cam ofthe engine cam shaft.` The lever is thereby given a positive stroke bythe active phase of the cam and imparts a positive suction stroke to thediaphragm. If the diaphragm is intended to have a constant stroke inboth directions, the lever will be returned during the passive phase ofthe cam by the compression discharge spring but if it is desired to havea variable discharge stroke of the diaphragm, the lever is connected bylost motion means to the stern of the diaphragm and is returned duringthe passive phase of the cam by a follower, spring reacting between thelever and the lower casing part of the pump. 'I'he diaphragm cooperateswith a pumping chamber provided with an inlet connection from the sourceof fuel supply and a discharge connection to the carbureter, the inletand discharge passages being controlled for one-way flow by ordinarycheck valves.

The fuel pump when installed in a motor vehicle is at a much greaterdistance from the fuel supply tank than from the carbureter and,therefore, it is desirable to develop a much higher suction pressure fordrawing the fuel from the supplytank into thel pumping chamber than themaximum discharge pressure required for delivering fuel to the floatchamber of the carbureter, for example, the maximum discharge pressuremay only be two inches of mercury while, in order to secure the desiredmaximum flow, the suction pressure should be as high as twelve inches ofmercury, or thereabouts.

If a constant stroke diaphragm is employed,

separate means must be provided, such as a bypass with apressure-controlled valve to prevent delivery to the carbureter when thefloat-actuated valve is closed. If thepressure-controlled by-pass is inthe usual position between .the pumping chamber and the inlet connectionaround the inlet check valve, it will be obvious that a high suctiondeveloped inthe chamber will tend to open the by-pass valve and,therefore, it is not possible to obtain a suction pres- 65 sure greaterthan the relativelyl low maximum discharge pressure permitted.Furthermore, if the pump is of the type in which the diaphragm has avariable discharge stroke with the compression discharge spring designedto be inoperative when the relatively low dischargepressure is reached,it will be obvious that when maximum delivery of the fuel is required,as for example,- with the vehicle running in high speed, the diaphragmwill be rapidly vibrating and the discharge spring will not havesufficient strength t0. fully react in the short interval permitted bythe rapid movements of the actuating lever.

It is a purpose of the present invention to pro-l vide an improvement ina fuel pump whereby the above-noted objections in the previous design offuel pump are removed and the present construction contemplates theprovision of a pressurecontrolled valve on the discharge side of thepump beyond the outlet check valve which is normally 85 opened to permitfull flow of the fuel throughv the delivery line but which will be movedto seated position in the direction of fuel flow when the relatively lowmaximum discharge pressure is reached. Since this valve seats in thedirection of fuel flow, further delivery of fuel from the pumpingchamber is positively prevented and with the form of pump shown, aconstant stroke diaphragm and a pressure-controlledby-pass is provided,the pressure at which the by-pass valve opens may be made as high asdesirable so as to be unaffected by the high suction pressure in theinlet line while, on the other hand, in the case of a pump with avariable stroke diaphragm, the strength of the compression springinstead of being limited by the relatively low maximum pressure may bemuch stiffer so as to react more quickly during high speed operation formaximum delivery of fuel.

According to the broadest phase of the invention, it will be apparentthat the discharge pressure controlling valve may be anywhere in theline between the pumping chamber and the float chamber of the carbureterbut it is a specific ob# ject of the invention to so design the fuelpump pressure acting upon the diaphragm will cause the diaphragm to moveand permit the valve to be seated when the maximum discharge pressurehas been reached.

Further and additional objects of the invention will be more clearlyunderstood from the following detail description taken in connectionwith the attached drawings, in which- Figure 1 is a plan view of theexterior of a unitary fuel pump with the present improvement appliedthereto; V l

Figure 2 is a complete vertical section taken through the pump in amanner to most clearly illustrate the construction as indicated by 2-2in Figure 1;

Figure 3 is a detail horizontal section taken on the plane indicated by3--3 in Figure 2;

Figure 4 is a. detail section of a portion of the upper pump casing partillustrating the borings for the fuel passages;

Figure 5 is a plan view of a modified construction of the fuel pump;

Figure 6 is a complete vertical section taken on the plane indicated by6-6 on Figure 5, and

Figure 7 is a detail horizontal section taken on the plane indicated by7-7 in Figure 2.

The form of fuel pump illustrated in Figures 1 to 4 which is of the typehaving a constant stroke pumping element and a pressure-controlledby-pass will be first described. I'he pump casing consists of an uppercasing part 10 and a lower casing part 11 clamped together by bolts 12in the usual manner, holding therebetween a flexible diaphragm 13. Thelower casing part 11` has an integral boss 14 forming a guide bearingfor the stem 15 having a reduced upper end attached by a nut 16 insertedthereto tothe diaphragm 13 and further serving to clamp to the oppositesides of the diaphragm rigid disk members 17 and 18 which renderinflexible the central area of the diaphragm and the upper disk member17 being formed to prevent any slack in the diaphragm. A compressionspring 19 is mounted in a chamber 20 of the lower casing partsurrounding the boss 14 and serves to produce the discharge stroke ofthe diaphragm. An operating lever 21 is carried by a fulcrum pin 22mounted in a chamber 23 of the lower casing part and has a yoke end 24engaging the lower end of the stem 15 in a manner to accommodate thearcuate movement of the lever relative to the linear movement of thestern. The lever has a protruding arm 25 whereby, when the pump ismounted as shown 4on an engine casing 26, the end of the lever arm 25comes into thrust engagement with a cam 27 carried by an engine camshaft 28. It will be apparent from this form that the lever and thediaphragm will have constant strokes in both directions and the spring19 will serve to maintain the lever arm 25 in contact with the camduring the idle phase of the cam movement.

The upper casing part 10 has a lateral extension 29, shown in detail inFigure 4, with a straight bored passage 30 from the threaded inlet pipeconnection 31 to the pumping chamber 32. This passage is closed, asshown in Figure 2, by the, plug 33 so thatthe fuel is directed downwardas it flows in from the suction line through the vertical bored passage.34 into a fuel-'receiving trap chamber 35 formedfby the transparent cup36, held by detachable securing means indicated in general as 37 to thelower portion of the lateral extension. The cup 36 serves to hold inplace a filter 37 surrounding the vertical inlet passage 34 so that thefuel to reach the vertical passage 38,-in order to flow again into thepassage 30 on the other side of the plug 33, must pass through thefilter. The upwardly directed passage 38 is controlled by'a check valve39, seating on a valve seat member 40 and normally moved to seatedposition by spring 41. A threaded plug 42 -is mounted in the pumpextension 29 and includes a stem 43 holding the spring 41 into positionand having bored passages 44 therein. 'I'he upper end of the l plug 42forms a seat portion for a relief check valve 45 normally held in seatedposition by a spring 46 supported between a cap member 47 and the checkvalve, the cap member being formed of pressed metaland secured by bolts48 to the casing extension 29. It will be readily apparent that inordinary operation of the pump,Y

fuel will intermittently flow into the pumping chamber past the inletcheck valve 29 and, if the pressure in the pumping chamber becomesexcessive, the valve 45 will be lifted to permit the fuel to flow fromthe pumping chamber back towards the inlet pipe connection and the fuelwill be simply recirculated around the plug 33 through the passagesprovided.

The upper casing part 10 includes an upwardly directed extension 49having therein a delivery flow passage 50, a valve seat member 51 beingpressed into the extension 49 and cooperating with a check valve 52normally held in seated position by a spring 53. The extension 49includes therein a cylindrical portion 54 to which is attached at itsupper end a threaded plug 55 having outlet passages 56 for flow of thefuel into an enlarged chamber 57. The chamber is divided by a perforateddisk member 58 which forms a separating plate for the vapor and fuel sothat the upper portion of the chamber 57 constitutes a vapor dome whilethe delivery pipe connection 59 is made to the side of the extension 49below the plate 58. The perforated plate 58 is supported by the threadedplug 55. The plug 55 further., at its bottom, forms a seat for a conicalvalve 60 guided for movement by stem 61 extending through the upper endof the plug 55 so that the valve 60 seats in the direction of fuel flow.The valve 60 is urged' to its seating position by the same spring 53 asthe outlet check valve 52. 'I'he valve 60 is moved to its normally openposition by means of a diaphragm 62 and compression spring 63. Thediaphragm includes a rivet 64 securing disks 65 to the opposite sides ofthe dia-v phragm and positioned in thrust engagement at its lower endwith the upper rounded end of the valve stem `61. The diaphragm isclamped for assembly to the upper end of the extension 49 by the innerstop ring 66 and the upper cap member 67 secured by bolts 68. A l

The operation of the lpump will be readily understood. The spring 63 isadjusted to the desired discharge pressure and normally holds the valve60 in open position and the pump will operate in its customary mannerwith the diaphragm making aconstant stroke in both directions andserving to draw the fuel past the inlet check valve and deliver the fuelpast the outlet valve towards the carbureter. As soon as the vaporpressure inthe chamber 57 becomes sumcient, the diaphragm 62 will belifted thus allowing the valve 60 to be seated by the force of thespring 63 whereupon, since the discharge stroke of the pump diaphragmcan no longer deliver fuel past the outlet check valve, the by-passcheck valve 45 will be lifted against the resistance of the relativelystrong spring 46 and the fuel will. be re-circulated until the valve 60is again open to permit further delivery.

The compression spring 63 which acts upon the controlling diaphragm 62must necessarily be greater in strength than the spring 53 which reactsbetween the check valve 52 and the conical valve 60 in order that in thenormal operation of the pump the check valve 52 will be lifted therebycompressing the sp1-lng 53 but without producing any movement of thecontrolling diaphragm against the force of the compression spring 63.The stop ring 66 is therefore provided to limit the movement of thecontrolling diaphragm when assembled and during the normal operation ofthe pump; thus the lower disk member 64 will come into seatingengagement upon the stop member 66 and limit the normal open position ofthe conical valve 60, as shown in Figure 2. The preferred constructionin which the controlling diaphragm is mounted at the top portion of thevapor trap chamber is desirable since the fuel is kept out of contactlwith the controlling diaphragm and thus leakage at its connections isprevented.

Referring now to the form of construction illustrated in Figures 5, 6and 7, there is shown a type of fuel pump-in which the pumping diaphragmmay have a variable discharge stroke due to a lost motion connectionbetween the lever and the stem of the diaphragm. The pressure actuatingdischarge controlling valve is substantially similar in structure andoperation to that described with reference to the first embodiment but,instead of employing a recirculating valve, the relief of an excessivepressure in the pumping chamber is provided by the lost motion meansallowing a variable discharge stroke of the pumping diaphragm and withthis construction the compression spring which acts upon the pumpingdiaphragm may be much stiffer than that customarily employed.

The pump casing has an upper casing part 110 and a lower casing part 111clamped together by bolts 112 and 'securing therebetween a flexiblepumping diaphragm 113. The casing part 111 has an internal cylindricalboss 114 guiding the longitudinal lmovement of the pump stem 115 whichis attached by a threaded nut 116 to the diaphragm. Diaphragmcontrolling disks 117 and 118 are shown clamped to the opposite sides 0fthe diaphragm, as previously described. The compression discharge spring119 which reacts against the lower side of the pumping diaphragm issimilar to the spring 19, shown in Figure 2, but need not be as strongas the spring 19 since it does not provide the force for maintaining thelever in contact with the cam. Instead, the lever 121 carried by thefulcrum pin 122 has its yoke end 124 engaging a movable sleeve 124' uponthe lower end of a pump stem 115 adapted to come into engagement with astop member 115 secured to the lower end of the pump stem. Theprotruding varm 125 of the lever, when the pump is mounted on the enginecasing 126, comes into thrust engagement with the cam 127 upon the shaft128 and the lever is maintained in .contact with the cam during thepassive phase thereof by the follower spring 125' reacting between thepump. casing 111 and the arm 125 of the lever.

The construction so far described corresponds to the previous design offuel pump except that the strength of the spring 119 is not limited bythe maximum pressure at which the pump is permitted to deliver, but,instead may be sumciently strong to react quickly for the full dischargestroke of the diaphragm when the pump is being operated at high speedand therefore will give the maximum delivery of fuel from the pump. Theupper casing part'110 has a. lateral extension 129 formed with astraight bored passage 130 leading from the inlet pipe connection 131 tothe pumping chamber 132'. The passage is, however, closed by a plug 133and the fuel is caused to ow from the first portion of the horizontalpassage 130 downthrough the vertical passage 134 into the fuel receivingchamber 135 formed by the cap 136. Fuel flows upward from chamber 135through the filter screen 137 and through the vertical passage 138controlled by the check valve 139 seated upon a valve seat member 140.'The check valve is moved to its seating position by spring 141 which isheld at its upper end by the threaded end 142 mounted in the extension129.

'I'he pump casing part 110 has an integral upward extension 149surrounding avertical flow passage 150 formed in valve seat member 151controlled by check valve 152. The outlet check valve 152 is moved toits seating position by the spring 153. There is provided asubstantially cylindrical extension fronr the pump casing 153 closed atthe upper end by the threaded plug 155 having apertures 156 fordelivering fuel into the chamber 157. The chamber 157 is included withinthe pressed metal cylinder 149 which is seated upon and secured to thepump casing extension 149. A perforated transverse plate 158 separatesthe chamber 157 into upper and lower portions and serves as a combingplate for trapping the vapor in the upper portion of the chamber whilethefuel flows out through the outlet pipe connection 159. A conicalvalve 160 is provided seating in an upward direction against the lowerend of the threaded plug 155 and is guided for movement by a stem 161which extends through the upper end of the plug 155. The valve 160 iscontrolled by a flexible diaphragm 162 acted upon by a compressionspring 163. The diaphragm 162 has clamped to its opposite sides diskmembers 164'held by rivet 165, the rivet 165 being in a position to comeinto thrust engagement with the upper rounded end of the valve stem 161.diaphragm is assembled between a. stop ring 166 and a cap member 167clamped to the upper end of the pressed-metal cylinder 149' by bolt andnut connections 168. In the assembly, the spring 163 will besuiliciently strong to bring the diaphragm 162 into a stopped positionwith the lower disk member 164 seating upon the stop ring 166 and thevalve 160 will be urgedupwardly by the spring 153 and come into contactwith the diaphragm 162 and be held in normally open position.

The spring 153 is lighter than the compression spring 163 and,therefore, the reciprocations of the pumping diaphragm will developsufllcient pressure to open the outlet check valve without Thespring-pressed controlling and allow the valve 160 to be moved to itsseating position by the spring 163. When this occurs, further deliveryof fuel from the pumping chamber past the outlet check valve isprevented. In the rst embodiment, the pressure is relieved by theopening of the recirculating valve, but, according to the presentdescribed embodiment, thepressure in the pumping chamber becomessumcient to balance the force of the spring 119 acting upon the pumpingdiaphragm and prevent further pumping movements of the pumping dia-vphragm. Therefore, the lever 121 will continue to be moved for its fullstroke in both directions without causing any movement of the diaphragmdue to the lost motion movement of the spool 124' on the stem 115.

According to the previous forms of fuel pumps in which the pumpingdiaphragm has a variable dischargestroke determined by the force of thecompression discharge spring, the strength of the spring is limited bythe maximum discharge pressure at which the pump delivers and,therefore, at high speed operation, the discharge spring would not bestrong enough to react quickly enough in the short interval of timeallowed by the idle movement of the lever, but where a delivery pressureregulating valve is employed, as described in the present invention, thedischarge spring may be made much stronger in order to give a higherflow .during high speed operation of the pump.

I claim:

1. An apparatus for feeding fuel from a source to a place of useconsisting of a pump, fuel supply and delivery linesv connected thereto,a valve in the delivery line seating against back now to the pump, asecond valve in the delivery line beyond the first valve seating in thedirection of fuel flow, a spring reacting on said second valve holdingit normally open, means acted upon by the discharge pressure beyond saidsecond valve arranged to compress said spring and allow said secondvalve to seat when the discharge pressure reaches a predetermined amountand a second spring reacting between the two valves for seating bothsaid valves, said second spring being weaker than the first mentionedspring whereby the second mentioned valve is held normally open andoperates for applying pressure to the second spring in a direction forholding the flrst valve normally seated.

2. An apparatus for feeding fuel from a source to a place of useconsisting of a pump having a casing, fuel supply and delivery linesconnected thereto, an upwardly projecting portion of the pump casinghaving an upwardly directed flow passage and a lateral connectiondischarging towards said delivery line, a ilexible diaphragm closing theupper end of said upwardly projecting portion of said pump casing, acheck valve in the upwardly extending flow passage adapted to seatagainst back ilow to the pump, av second valve in the flow passage abovethe first valve, said second valve being engaged by said diaphragm to beheld normally open and a spring reacting between the valves forseatingboth of said valves whereby when the delivery pressure reaches apredetermined amount, said diaphragm will be moved to permit said secondvalve to seat.

3. 'An apparatus for feeding fuel from a source to a place of usecomprising a pump casing having a pumping chamber therein, a checkvalvel controlled inlet passage leading to said pumping chamber, vanupwardly directed check valve con-- trolled outlet passage leading fromsaid pumping chamber, a vapor trapping chamber at the upper end of saidoutflow passage, a laterally directed discharge connection at the lowerportion of said vapor trapping chamber and above the outlet check valve,a normally open valve in said upwardly directed flow passage below saidlaterally connected discharge connection and above the outlet checkvalve, a flexible diaphragm closing the top portion of said vaportrapping chamber adapted to engage said normally open valve and a springreacting upon said diaphragm tending to hold said valve normally open,whereby, when the delivery pressure in the vapor trapping chamberreaches a predetermined amount, said diaphragm will be moved against theforce of said spring and said normally open valve will be allowed toseat.

4. A unitary fuel pump adapted to be eamactuated by the engine fordelivering fuel from a supply tank to a carbureter of an engine, apumping chamber therein, a delivery passage leading therefrom, a checkvalve controlling said delivery passage for one-way flow therethrough, achamber in said delivery passage on the discharge side of said checkvalve, an outflow connection below the top of the chamber, a exiblediaphragm closing the top of said chamber and a valve in the deliverypassage normally held in open position by said diaphragm whereby thevapor pressure trapped in said chamber and acting on said diaphragmcauses the closing movement of said valve to prevent the passage of fuelto the discharge side of said valve.

5.`In a fuel pump construction, an upwardly directed delivery passagefrom the pumping chamber, a check valve controlling said passage forone-way flow therethrough, a second valve above said first-mentionedcheck valve adapted to seat in a direction of fuel flow and a springreacting between said valves tending to urge said valves to seatedpositions and means for normally holding said second valve in openposition.

6. `In a fuel pump construction, a pump casing having a pumping chambertherein, said casing including an upwardly directed projectioncontaining an outflow passage, a flexible diaphragm secured to saidprojection closing the upper end thereof, a cap member secured to saidprojection on the exterior of said diaphragm, a compression springenclosed within said cap member reacting upon said diaphragm in adirection to move said diaphragm downwardly, a

stop member within said projection limiting the downward movement ofsaid diaphragm, a valve within said yprojection having an upwardlydirected stem adapted to engage said diaphragm by said valve normallyheld in open position, a check valve below said first-mentioned valveand a spring reacting between said valves for normally seating saidcheck valves whereby said last-mentioned spring causes saidfirst-mentioned valve to seat in a direction of fuel flow when saiddiaphragm has been upwardly moved by the delivery pressure.

EDWARD A. ROCKWELL.

